Avi Load Balancer may close active connections to pool servers when there is a pool configuration change

Products

• VMware Avi Load Balancer

Issue/Introduction

When pool servers are added by DNS, there is a refresh interval which resolves the pool server hostnames (every 60 minutes by default).
If a pool DNS refresh happens and a pool server IP is removed on the DNS refresh, the default behavior will result in closing of all the connections to the back-end server that was removed. 

Resolution

To prevent this behavior and allow the active connections to complete, you can set the value for "delete_server_on_dns_refresh" = False in the pool settings via the CLI. This will only reject any new connections to the server and existing connections will remain open.

To configure this, ssh to the controller leader node.
Type shell to enter the Avi shell (and authenticate).
Then enter the following commands:

[admin:controller]: > configure pool [pool name]
[admin:controller]: pool> no delete_server_on_dns_refresh
[admin:controller]: pool> save
[admin:controller]: >

After saving the change, the setting should then be enabled.